Bevel gears are widely used in trucks, construction vehicles and mining machinery. The current trend is that the potential is still in growing. At present, there are mainly two versions of bevel gears in the market. The first type is the bevel gears manufactured by Gleason, Germany (about 90% m/s), and the second type is the bevel gears manufactured by Klingelnberg, Germany (about 10% m/s). Thousands of tools for face hobbing Gleason version bevel gears exist in the market.
In typical processes of face hobbing bevel gears, the milling cutter and the workpiece rotate independently in a timing relationship with each other, thereby allowing continue indexing of the workpiece and continual formation of the gear teeth. Thus, in most of the face hobbing processes, a single plunge of the cutting tool can result in all the teeth of the gear being formed.
In the current industry, tool bits of high speed steel (HSS) are predominantly employed to face hob the spiral bevel gears. Alternatively, blades of high speed steel or solid carbide blades with various coatings are employed to face hob the spiral bevel gears. The blades can be re-sharpened and re-coated, which, however, consumes time and requires high cost. The existing cutting tools are also adjustable in radial and angular planes. Gleason version cutting tools have several styles in order to meet requirements on low and high volume production, and roughing to finishing machining.
U.S. Pat. No. 6,715,986 and U.S. Pat. No. 6,086,291 disclose a grooving insert, which can be used for milling tooth roots. German patent DE 20016673 discloses a milling cutter assembly, which can be used for milling tooth flanks, and in which inserts having rectangular basic shapes are employed. U.S. Pat. No. 6,632,050 B2 discloses a face hobbing cutter system, in which blades are employed. Chinese patent CN 00807087.3 discloses a face hobbing cutter system for face hobbing gears. U.S. Pat. No. 6,609,858 and U.S. Pat. No. 7,736,099 disclose cartridged, face hobbing cutter systems. For example, FIG. 1 shows an exploded perspective view of the face hobbing cutter system of U.S. Pat. No. 7,736,099, wherein the reference sign 1 denotes the gear milling cutter system, the reference sign 2 denotes the cutter disc, the reference sign 3 denotes the top surface of the cutter disc, the reference sign 4 denotes the cartridge assemblies, the reference sign 5 denotes the side surface of the cutter disc, and the reference sign 6 denotes the slots. In the face hobbing cutter system shown in FIG. 1, the cartridge assemblies 4 are arranged in two rows, i.e., an inside row and an outside row, for respectively milling the inner side and the outer side of the gear teeth, and the cartridge assemblies each include a cartridges and an indexable insert, all the cartridges and inserts being the same.
However, the disadvantages generally existing in current face hobbing cutter systems are as follows: due to the employment of the high speed steel tool bits or the solid carbide blades to machine the spiral bevel gears, the productivity is comparatively low, a wet machining is required (i.e., a cooling liquid is required), the set-up time is long, and the cost and time for replacing the tool bits or regrinding the blades is high. In the existing milling cutter system employing cartridge assemblies with indexable inserts, all the cartridges and inserts are the same, and the machining result is still not satisfactory. Accordingly, there exits a need for a bevel gear face hobbing cutter system achieving high productivity, dry cutting and less set-up time. In addition, it is expected to improve the life of the cutting tool.